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    <title>Document</title>
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    //获取cookie值的函数
    getCookie=(cname)=>{
        var name = cname + "="
        var ca = document.cookie.split(';')
        for (var i = 0; i < ca.length; i++) {
            var c = ca[i].trim()
            if (c.indexOf(name) == 0) return c.substring(name.length, c.length)
        }
        return ''
    }
    console.log(getCookie('qwer'))


    //设置cookie值得函数
    setCookie=(cname,cvalue,exdays)=>{
        var d=new Date()
        d.setTime(d.getTime()+(exdays*24*60*60*1000))
        var expires='expires='+d.toGMTString()
        document.cookie=cname+'='+cvalue+';'+expires
    }
    setCookie('qwer','000',1)


    //检测cookie值的函数
    checkCookie=()=>{
        var username=getCookie('username')
        if(username!=''){
            alert('欢迎'+username)
        }else{
            username=prompt('请输入你的名字:','')
            if(username!=''&&username!=null){
                setCookie('username',username,2)
            }
        }
    }
    checkCookie()
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